Wikipedia:Reference desk/Archives/Mathematics/2014 May 2

= May 2 =

How do I unroll the circumference of a circle as in this picture?
How do I unroll the circumference of a circle as in this picture?

http://upload.wikimedia.org/wikipedia/commons/2/2a/Pi-unrolled-720.gif — Preceding unsigned comment added by 37.238.19.174 (talk) 16:12, 2 May 2014 (UTC)


 * You want to know how to make an animated GIF like that one ? Do you have a computer programming background ?  First you'd want to create a "primitive" (the wheel shape, skipping the outside edge), then change it's rotation and translate the horizontal coord of the center at each frame.  You'd also need some background graphics, like the number line and PI symbol.  Finally you'd need to add some logic to "unpeel" the circle, only drawing a portion of it with each frame, with the remainder on the number line.  This could all probably be done in a few hours.


 * Also, are you asking about the mechanics of stitching frames together to form an animated GIF ? I suggest using ImageMagick to do that.  See some examples of animated GIFs I created using ImageMagick at the bottom of my home page (you need to click to open each one up).   StuRat (talk) 17:54, 2 May 2014 (UTC)


 * I should also add that you are likely to want to work in polar coords (angle plus radius) for the wheel portion of the pic, and then convert that to rectangular coords (X and Y) for plotting. The polar coords will allow for easier rotation of the spokes in the wheel.  StuRat (talk) 23:03, 4 May 2014 (UTC)